As a contestant on America's Next Top Model, she was praised by Tyra Banks for her "symmetrical fantasticness", but writing in Cosmo, she discussed the cruel taunts she received from other kids.
Harlow - also known as Chantelle Brown-Young, has the skin condition vitiligo, which means that the cells that produce the chemical melanin die or stop functioning, causing white patches to form on the skin.
She explained that children at school had been warned to stay away from her, "because they might catch my skin condition" - despite the fact that vitiligo is not contagious.
From the third grade, "it would define the way people treated me," Harlow wrote, describing the way that "kids called me a cow and mooed at me."
She went on to describe how the bullying changed from name-calling to physical violence:
One night at a basketball game, I sat by myself while a girl mooed at me. I turned around and rolled my eyes. She kept mooing, and I told her to stop. A group of older kids prodded her, saying, "You're gonna let her talk to you like that?" After the game, outside in the cold, she rushed toward me, shoving me.
People crowded around us. I didn't want to fight. With vitiligo, my skin is sensitive in extreme temperatures. To get out of the situation, I let her beat me up. The next day, she came at me again. This time, I snapped, defending myself extremely well. I never had to fight her again. But it was only the first of many similar incidents.
As the bullying continued, Harlow began to miss school, and was eventually recommended to move to another one. "It's crazy that I got ousted, when I was the one getting abused," she said.
But it was at this point that Harlow's life started to change - away from the bullies, she was able to perform better at school, and started to receive the encouragement that gave her the confidence to try and get noticed by Tyra Banks for America's Next Top Model. Which she did - and from there on, began to shake up the fashion industry's tired perceptions about what beauty looks like.
Harlow has since led the way in bringing diversity to the fashion industry, having walked the runway at this year's Madrid and New York fashion weeks, as well as acting as a brand ambassador for Desigual and Diesel.
But the bullying she faced has inspired her to do good. Harlow says that she recently returned to her school, "where I once cried in the hallways" to talk to the students about being confident and supporting one another.
And instead of anger, Harlow has found understanding for her childhood bullies: "Looking back, I can see that the students who bullied me were just like me, trying to fit in."